[gdal-dev] Data type of DATE in SpatiaLite

[Even Rouault]

> > On reading, the SQLite driver will currently only accept data with stored
> > as text (speaking here about the content of each cell, not the declared
> > column type!) and will try to parse them as ISO-8601. If the values are
> > stored as floating point or integer values, it will report null. It
> > might be good to implement the rule at 1.2 Date and Time Datatype of
> > https://www.sqlite.org/datatype3.html to convert from Julian days or Unix
> > time.

I've added support to recognize floating point values in a Date/DateTime column 
and convert from Julian fractional days to the expanded representation used by 
GDAL. Only on reading. If you create/update records, they will be output as 
ISO-8601 text.

> 
> I agree and I think that on the Spatialite side it might be good to make
> the spatialite tools to declare the columns which are known to contain
> dates/times as DATE/DATETIME even those types do not really mean anything
> for SQLite and huge amounts of existing and future Spatialite databases
> hold dates and times in columns which are declared as TEXT, INTEGER,
> DOUBLE, or without a type at all.
> 
> All in all, handling dates is the typeless SQLite in a reliable and
> interoperable way seems to be a bit complicated. I will think about writing
> a line or two into http://www.gdal.org/drv_sqlite.html about how GDAL plays
> with them once I understand it myself.
> 
> -Jukka-
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